What message characteristic can you configure within the SMTP-proxy policy to restrict email messages?

Configuring the sender's Mail From address within the SMTP-proxy policy allows you to establish rules regarding which email messages are accepted or rejected based on the originating address. This is particularly useful for filtering out unwanted or potentially malicious emails from specific senders. By specifying certain Mail From addresses, you can effectively manage the type of emails that are allowed through your firewall, thereby enhancing security and reducing spam.

While other options provide useful functionalities for managing email, such as checking URLs for safety or enforcing file size limits, they do not specifically restrict emails based on the sender's address. Thus, configuring the sender's Mail From address stands out as a direct approach to controlling the flow of email messages in relation to their source.